New research shows that vegans who are meat- and dairy-free for the animal-saving, rather than the promise of a slimmer waistline, are a lot more likely to stick to it.

As we learned from the results of a Humane Research Council study late last year, vegetarians are actually a pretty fickle bunch. In fact, 83 percent of them end up defecting—make that a slightly less pathetic 70 percent for vegans. Two-thirds of vegetarian defectors were women, and the primary reason why they had first turned to the meat-free lifestyle was for the health benefits. You know—weight loss, lower blood pressure, and decreased risks of developing heart disease and cancer.

Despite these incentives, less than half of them had made it even a full year on the diet, seemingly unable to embrace a never-ending regimen of quinoa, kale, green smoothies, and beet patties.

But here's the good news, per new research: their friends who are in it for the animal-savin', rather than the promise of a slimmer waistline, are a lot more likely to stick to it. Researchers from Fairleigh Dickinson University and Benedictine University have found that ethical vegans stick to their seitan an average of two-and-a-half-years longer than their ascetic, jicama-munching counterparts who care less about animals and more about their own health.

Researchers surveyed 246 vegans for the study, which is published in the newest edition of Appetite, and found that while health-focused vegans are less likely to indulge in sweets and other junk food (hey, not all meat- and dairy-free foods are good for you), they're also less committed to being plant-based. The average health-focused vegan in the study stuck to it for five-and-a-half years, while the average ethical vegan lasted for eight before bailing.

Interestingly, ethical vegans seemed more consumed about nutrition in another aspect: they were more likely to take vitamin supplements. This may indicate that some of the "healthy vegans" actually knew less about plant-based nutrition, and assumed that cutting out animal products was inherently healthier without doing the full research about which nutrients and minerals (such as B-12 and iron) need to be monitored in terms of blood levels.

But hey—morals are generally less flexible than health fads. Add on the fact that the Dietary Guidelines Advisory Committee just released new recommendations that name a vegan diet as the best choice for health and environmental soundness.